In order to examine samples, in particular tissue samples, using a microscope, the tissue samples frequently need to be prepared for this purpose. In particular, the samples need to be cut into extremely thin sections so that they can be examined with the microscope. Sectioning of the tissue samples is commonly done using microtomes. To enable accurate sectioning of the tissue samples, the samples are initially subjected to a treatment process. For example, they may be embedded in paraffin blocks. The embedding of the samples can be done using generally known tissue processors, which include a plurality of containers containing process media. In order to carry out the treatment, the samples are either placed in the containers, or in a retort which is provided for sample treatment and into which the process media are pumped from the containers.
When using process media, it is generally required to maintain the process parameters within predetermined limits. For example, when paraffin is used as a process medium, the paraffin is maintained at a predetermined desired temperature with an accuracy of ±2K, firstly to keep the paraffin in the liquid state, and secondly to prevent the additives contained in the paraffin from being damaged by overheating. In order to measure the temperature of the process media, it is known to provide a temperature sensor which measures the temperature of a container containing one or more process media. The process media temperature can be controlled to a predetermined desired value, or to different predetermined desired values, using a heating device.
During operation of the tissue processor, the containers are in their working position, in which the process medium is pumped out of or into the container. If during operation of the tissue processor, one of the containers is not in its predetermined working position, either because it was not placed in the tissue processor at all, or because it has not been completely brought into its working position, process medium may leak from the connections, conduits and/or from the tissue processor, contaminating the tissue processor or the environment surrounding it and/or impairing the proper functioning of the tissue processor. In addition, leaking hot or harmful process media can cause injury to operating personnel.